Screen for wood pulp, etc.



S. THUNE SCREEN FOR wooD PULP,

ETC

Filed Dec. 12, 1924 Patented Dec. 22, 1925.

UNITED STATES SYERRE THNE, OFSKOIEN, NEAR C-HRISTIANIA, NORWAY.

SCREEN FOR WOOD PULP, ETC.

Application and December-12,1924. seriai No. 755,406.

To all whom it my ooi-wem:

Be 1t known that I, SvERnE THNE, a subject of the King of Norway, residing at Skoien, near Christiania, Norway, have invented certain new and useful Improvements in Screens for Wood-Pnl Etc.; and

l lI do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others' skilled in the art to which it. appertains to make and use the same, reference being had to the accompanying drawings, and to letters or figures of reference marked thereon, which form a part of this speciication.

The present invention has for its object a screen for wood pulp, etc., and comprises a screening drum which rotates rapidly in a closed casing.- The pulsations which serve to kee the screening surface clean are produced giving the inner surface of the casing enclosing the screening drum such a form that the distance between the said inner surface and the screening drum is alternately shorter and longer. i

Two forms of the invention'are illustrated on the drawing, where Figs. 1 and 2 show cross said two forms. l Y Y 1 is the casing which is made in the form of a closed vessel with six edges or extensions and is provided with intake 2 and outlet 3. 4 is the rotating able intervals is provided with radial vanes 5. The casing 1 as stated above has not a regular cross section, but as illustrated on the drawing is extended at the top (6)' between intake and outlet and is provided at the top with an air intake tube 7. The inside of drum 4 is provided with an outlet for screened pulp as indicated at 8.

On Fig. 2 is illustrated another form of outlet for the screened pulp. According to this form of the invention the pulp is removed by means of a stationary curved 'tube 10.

The apparatus operates in the following manner:

The unscreened pulp is introduced at 2 and is caused by means of the rotating drum with vanes 5to flow with high velocity in the annular space between screening drum 4 and casing 1. The centrifugal force ysections of the will cause the liquid pulp to follow the inside surface of the casing and fill the s ace between screening drum 4 and the wal of the casing. Owing to the varying distance fective cleanin screen which at suit-v between the screening surface and the 1nside surface of the casing,A the pul liquid will be caused to pulsate in both directions through tlie screen openings, whereby the desired screening effect is increased.

It has been proved advanta ecus, particulai-ly. with the form illustratetgl on Fig. 1, to provide an air intake tube, at the top of the casing.

The air sucked in through tube or tubes 7 will pass through the openings in the screening druin and form anl air bubble 9 inside the drum. This air bubble reduces the depth of liquid, whereby a very efof the screening surface is obtained. T is eiect is most prominent at the top of the screening drum, where the casing is also provided with the above mentioned extension 6 in order that the screenin surfaceshall be completely free from pu p liquid, before coming in touch with the new pulp, introduced at intake 2. The radial depth of liquid inside the screening may be reduced by mounting one or i more stationary outlet tubes 10 (see Fig. 2)

which are so curved as to take u and conduct the screened pulp to the out et.

Claims y1. Screen, for woodpul etc., comprisin a closed casing, an inta e for unscreen pulp therein, a rotatingA screening drum mounted inside said closed casing, an outlet for screened pulp from the inside ofl said 'rotating drum, the inner surface of said closed casing having such a form that the radial distance between said inside surface and the screening surface varies along the circumference of the casing. 2. Screen for'wood pulp, etc., comprisin a closed casing, an inta e for unscreene pulp therein, a rotating screening drum mounted inside said closed casing, an outlet for screened pulp from the inside of said rotating drum, the inner' surface of said closed casing having such a form, that the radial distance between said inside surface and the screening surface varies along the circumference of the casing and being also providedwith one or more enlargements which are wider than the rest, with the object of obtaining a thorough cleaning of the screening surface one or more oi-nts.

3. Screen for wood pu p, etc., comprising a closed casing, an intake for unscreened p'ulp therein, a rotating screening drum mounted inside said closed casing, an outilo let for screened pulp from the inside of said rotating drum, the inner surface o said closed casing having such a form that the radial distance between said inside surface and the screening surface varies along the circumference of the casing and an air intake at the top of the closed casing with the object of forming an air-bubble, -so as vto reduce the depth of liquid above the highest point of the screening drum for the purpose of obtaining a thorough cleaning of the screening surface at this point.

4. Screen for Wood pulp, etc., comprising a closed casing, an intake for unscreened pulp therein, a rotating screening drum mounted inside said closed casing, an out- `let for screened pulp from the inside of said rotating drum, said outlet having the form of a scoop, adapted vto carry away the rotating liquid, theinner surface of said closed casing having such a form that the radial distance between' said inside surface and the screen surface varies along the circumference of the casing.

In testimony that I claim the foregoing as my invention, I have signed my name.

SVERRE THNE. 

